I just downloaded and built libgpg-error 1.33 on macOS 10.13.6 (High Sierra). It built successfully, but I see a bunch of compiler warnings that I don't recall seeing before. They all look like this (but the "file included from" changes):
In file included from posix-lock.c:42: ./gpgrt-int.h:467:9: warning: 'snprintf' macro redefined [-Wmacro-redefined] #define snprintf _gpgrt_estream_snprintf ^ /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk/usr/include/secure/_stdio.h:56:9: note: previous definition is here #define snprintf(str, len, ...) \ ^ 1 warning generated.